organic compounds
5-Amino-1H-pyrazol-2-ium hydrogen succinate
aDepartment of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India, and bDepartment of Chemistry, Keene State College, 229 Main Street, Keene, NH 03435-2001, USA
*Correspondence e-mail: jjasinski@keene.edu
In the cation of the title salt, C3H6N3+·C4H5O4−, the protonated pyrazolium ring is planar (r.m.s. deviation = 0.012 Å). An intramolecular C—H⋯O hydrogen bond occurs in the anion. In the crystal, N—H⋯O hydrogen bonds and a weak C—H⋯O interaction between the cations and anions form two sets of R22(8) graph-set ring motifs. Intermolecular O—H⋯O hydrogen bonds between these lead to a criss-cross pattern along the b axis. In addition to the classical hydrogen bonds, a weak C—H⋯π(pyrazolium) interaction is observed and contributes to crystal packing. All of these interactions link the molecules into a two-dimensional supramolecular framework parallel to (10-1).
CCDC reference: 982974
Related literature
For the broad spectrum of biological properties of pyrazoles, see: Hall et al. (2009) and for their biological and medicinal activities, see: Vinogradov et al. (1994). For succinic acid derivatives used in chemicals, food and pharmaceuticals, see: Sauer et al. (2008). For related structures, see: Kavitha et al. (2013); Kettmann et al. (2005); Koziol et al. (2006); Parvez et al. (2001); Yamuna et al. (2013).
Experimental
Crystal data
|
Data collection: CrysAlis PRO (Agilent, 2012); cell CrysAlis PRO; data reduction: CrysAlis RED (Agilent, 2012); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: SHELXL2012 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2.
Supporting information
CCDC reference: 982974
10.1107/S1600536814001615/tk5290sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536814001615/tk5290Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536814001615/tk5290Isup3.cml
A mixture of commercially available 3-aminopyrazole (0.5 g, 6.02 mmol) and succinic acid (0.71 g, 6.02 mmol) were dissolved in 5 ml of hot dimethylsulfoxide. The reaction mixture was stirred for 15 mins at 323 K. The resulting solution was allowed to cool slowly at room temperature upon which X-ray quality crystals of the title salt were obtained after few days; M.pt: 368–373 K.
The N-bound H2A and H3A atoms were located by a difference map and refined isotropically. All of the remaining H atoms were placed in their calculated positions and then refined using the riding model with atom—H lengths of 0.93Å (CH); 0.97Å (CH2); 0.82Å (OH) or 0.86Å (NH). Isotropic displacement parameters for these atoms were set to 1.2 (CH, CH2, NH) or 1.5 (OH) x Ueq of the parent atom.
Pyrazoles comprise an important class of
and many pyrazole derivatives are reported to have a broad spectrum of biological properties, such as anti-bacterial and anti-inflammatory activities, anti-cancer (Hall et al., 2009). The chemistry of aminopyrazoles has been extensively investigated in the past. The considerable biological and medicinal activities of pyrazoles (Vinogradov et al., 1994), for which aminopyrazoles are preferred precursors, have stimulated these investigations. Succinic acid derivatives are also mostly being used in chemicals, food and pharmaceuticals (Sauer et al., 2008). Recently, the of 3-aminopyrazolium trifluoroacetate (Yamuna et al., 2013) was reported from our research group. Some other structures of related compounds, viz., 4-[bis(4-fluorophenyl) methyl]-1-[(2E)-3-phenylprop-2-en-1-yl]piperazin-1-ium 3-carboxypropanoate (Kavitha et al., 2013), doxylamine hydrogen succinate (Parvez et al., 2001), 5-amino-4-methylsulfonyl-1-phenyl-1H-pyrazole (Kettmann et al., 2005) and ethyl 1-acetyl-3-amino-1H-pyrazole-4-carboxylate (Koziol et al., 2006) have also been reported. In continuation of our work on pyrazoles, this paper reports the of the title salt, 5-amino-1H-pyrazol-2-ium hydrogen succinate, C3H6N3+.C4H5O4-, (I).The title salt, (I), crystallizes with one independent monocation (A) and a monoanion (B) in the
(Fig. 1). In the cation the protonated pyrazolium ring is planar. In the crystal, N—H···O hydrogen bonds involving two hydrogen atoms on the amino group (H1AA, H1AB), a N2A—H2A···O3B intermolecular hydrogen bond and a weak C2A—H2AA···O1B intermolecular interaction between cations and anions form two sets of R22(8) graph set ring motifs (Fig. 2). Intermolecular O—H···O hydrogen bonds between the anions leads to a criss-cross pattern along the b axis. In addition to the classical hydrogen bonds, a weak C—H···Cg(pyrazolium) intermolecular interaction is observed and contributes to crystal packing. All of these interactions directly link the molecules into a 2D supramolecular framework along (1 0 -1).Pyrazoles comprise an important class of
and many pyrazole derivatives are reported to have a broad spectrum of biological properties, such as anti-bacterial and anti-inflammatory activities, anti-cancer (Hall et al., 2009). The chemistry of aminopyrazoles has been extensively investigated in the past. The considerable biological and medicinal activities of pyrazoles (Vinogradov et al., 1994), for which aminopyrazoles are preferred precursors, have stimulated these investigations. Succinic acid derivatives are also mostly being used in chemicals, food and pharmaceuticals (Sauer et al., 2008). Recently, the of 3-aminopyrazolium trifluoroacetate (Yamuna et al., 2013) was reported from our research group. Some other structures of related compounds, viz., 4-[bis(4-fluorophenyl) methyl]-1-[(2E)-3-phenylprop-2-en-1-yl]piperazin-1-ium 3-carboxypropanoate (Kavitha et al., 2013), doxylamine hydrogen succinate (Parvez et al., 2001), 5-amino-4-methylsulfonyl-1-phenyl-1H-pyrazole (Kettmann et al., 2005) and ethyl 1-acetyl-3-amino-1H-pyrazole-4-carboxylate (Koziol et al., 2006) have also been reported. In continuation of our work on pyrazoles, this paper reports the of the title salt, 5-amino-1H-pyrazol-2-ium hydrogen succinate, C3H6N3+.C4H5O4-, (I).The title salt, (I), crystallizes with one independent monocation (A) and a monoanion (B) in the
(Fig. 1). In the cation the protonated pyrazolium ring is planar. In the crystal, N—H···O hydrogen bonds involving two hydrogen atoms on the amino group (H1AA, H1AB), a N2A—H2A···O3B intermolecular hydrogen bond and a weak C2A—H2AA···O1B intermolecular interaction between cations and anions form two sets of R22(8) graph set ring motifs (Fig. 2). Intermolecular O—H···O hydrogen bonds between the anions leads to a criss-cross pattern along the b axis. In addition to the classical hydrogen bonds, a weak C—H···Cg(pyrazolium) intermolecular interaction is observed and contributes to crystal packing. All of these interactions directly link the molecules into a 2D supramolecular framework along (1 0 -1).For the broad spectrum of biological properties of pyrazoles, see: Hall et al. (2009) and for their biological and medicinal activities, see: Vinogradov et al. (1994). For succinic acid derivatives used in chemicals, food and pharmaceuticals, see: Sauer et al. (2008). For related structures, see: Kavitha et al. (2013); Kettmann et al. (2005); Koziol et al. (2006); Parvez et al. (2001); Yamuna et al. (2013).
A mixture of commercially available 3-aminopyrazole (0.5 g, 6.02 mmol) and succinic acid (0.71 g, 6.02 mmol) were dissolved in 5 ml of hot dimethylsulfoxide. The reaction mixture was stirred for 15 mins at 323 K. The resulting solution was allowed to cool slowly at room temperature upon which X-ray quality crystals of the title salt were obtained after few days; M.pt: 368–373 K.
detailsThe N-bound H2A and H3A atoms were located by a difference map and refined isotropically. All of the remaining H atoms were placed in their calculated positions and then refined using the riding model with atom—H lengths of 0.93Å (CH); 0.97Å (CH2); 0.82Å (OH) or 0.86Å (NH). Isotropic displacement parameters for these atoms were set to 1.2 (CH, CH2, NH) or 1.5 (OH) x Ueq of the parent atom.
Data collection: CrysAlis PRO (Agilent, 2012); cell
CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis RED (Agilent, 2012); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: SHELXL2012 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).Fig. 1. ORTEP drawing of (I) (C3H6N3+.C4H5O4-) showing the labeling scheme with 30% probability displacement ellipsoids. Dashed lines indicate a C3A—H3AA···O1B intermolecular hydrogen bond linking the cation and anion within the asymmetric unit. | |
Fig. 2. Molecular packing for (I) viewed along the a axis. Dashed lines indicate O—H···O, N—H···O hydrogen bonds and weak C—H···O intermolecular interactions forming R22(8) graph set ring motifs. H atoms not involved in hydrogen bonding have been removed for clarity. |
C3H6N3+·C4H5O4− | F(000) = 848 |
Mr = 201.19 | Dx = 1.543 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 18.525 (3) Å | Cell parameters from 1155 reflections |
b = 6.7872 (9) Å | θ = 3.2–32.9° |
c = 14.564 (3) Å | µ = 0.13 mm−1 |
β = 108.900 (18)° | T = 173 K |
V = 1732.4 (5) Å3 | Irregular, colorless |
Z = 8 | 0.32 × 0.24 × 0.12 mm |
Agilent Eos Gemini diffractometer | 2922 independent reflections |
Radiation source: Enhance (Mo) X-ray Source | 1925 reflections with I > 2σ(I) |
Detector resolution: 16.0416 pixels mm-1 | Rint = 0.053 |
ω scans | θmax = 33.0°, θmin = 3.2° |
Absorption correction: multi-scan (CrysAlis PRO and CrysAlis RED; Agilent, 2012) | h = −11→27 |
Tmin = 0.591, Tmax = 1.000 | k = −9→9 |
5745 measured reflections | l = −22→20 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Hydrogen site location: mixed |
R[F2 > 2σ(F2)] = 0.071 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.212 | w = 1/[σ2(Fo2) + (0.1004P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.08 | (Δ/σ)max < 0.001 |
2922 reflections | Δρmax = 0.36 e Å−3 |
136 parameters | Δρmin = −0.40 e Å−3 |
0 restraints |
C3H6N3+·C4H5O4− | V = 1732.4 (5) Å3 |
Mr = 201.19 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 18.525 (3) Å | µ = 0.13 mm−1 |
b = 6.7872 (9) Å | T = 173 K |
c = 14.564 (3) Å | 0.32 × 0.24 × 0.12 mm |
β = 108.900 (18)° |
Agilent Eos Gemini diffractometer | 2922 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO and CrysAlis RED; Agilent, 2012) | 1925 reflections with I > 2σ(I) |
Tmin = 0.591, Tmax = 1.000 | Rint = 0.053 |
5745 measured reflections |
R[F2 > 2σ(F2)] = 0.071 | 0 restraints |
wR(F2) = 0.212 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.08 | Δρmax = 0.36 e Å−3 |
2922 reflections | Δρmin = −0.40 e Å−3 |
136 parameters |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | ||
O1B | 0.43675 (7) | −0.1627 (2) | 0.31692 (11) | 0.0344 (4) | |
H1B | 0.3996 | −0.1991 | 0.2719 | 0.052* | |
O2B | 0.49764 (7) | 0.1136 (2) | 0.36893 (11) | 0.0333 (4) | |
O3B | 0.32006 (7) | 0.6651 (2) | 0.19603 (10) | 0.0272 (3) | |
O4B | 0.26029 (7) | 0.3890 (2) | 0.13537 (12) | 0.0363 (4) | |
C1B | 0.44071 (9) | 0.0315 (3) | 0.31702 (12) | 0.0229 (4) | |
C2B | 0.37281 (9) | 0.1414 (3) | 0.25149 (13) | 0.0218 (4) | |
H2BA | 0.3292 | 0.1173 | 0.2729 | 0.026* | |
H2BB | 0.3608 | 0.0904 | 0.1860 | 0.026* | |
C3B | 0.38592 (9) | 0.3623 (3) | 0.24999 (13) | 0.0230 (4) | |
H3BA | 0.4014 | 0.4112 | 0.3161 | 0.028* | |
H3BB | 0.4276 | 0.3861 | 0.2248 | 0.028* | |
C4B | 0.31721 (9) | 0.4781 (3) | 0.18995 (12) | 0.0228 (4) | |
N1A | 0.63879 (8) | 0.9224 (2) | 0.48607 (12) | 0.0309 (4) | |
H1AA | 0.6782 | 0.9940 | 0.5136 | 0.037* | |
H1AB | 0.5988 | 0.9745 | 0.4456 | 0.037* | |
N2A | 0.70115 (8) | 0.6414 (2) | 0.56897 (12) | 0.0253 (4) | |
H2A | 0.7424 (17) | 0.704 (4) | 0.617 (2) | 0.057 (8)* | |
N3A | 0.68467 (8) | 0.4473 (2) | 0.57546 (12) | 0.0266 (4) | |
H3A | 0.7227 (16) | 0.354 (4) | 0.603 (2) | 0.051 (8)* | |
C1A | 0.63984 (9) | 0.7296 (3) | 0.50616 (12) | 0.0230 (4) | |
C2A | 0.58387 (9) | 0.5854 (3) | 0.46966 (13) | 0.0258 (4) | |
H2AA | 0.5358 | 0.6031 | 0.4241 | 0.031* | |
C3A | 0.61415 (10) | 0.4134 (3) | 0.51456 (14) | 0.0272 (4) | |
H3AA | 0.5897 | 0.2918 | 0.5044 | 0.033* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1B | 0.0265 (7) | 0.0171 (7) | 0.0430 (8) | 0.0006 (5) | −0.0117 (6) | 0.0017 (6) |
O2B | 0.0216 (6) | 0.0230 (7) | 0.0404 (8) | −0.0020 (5) | −0.0107 (5) | 0.0005 (6) |
O3B | 0.0237 (6) | 0.0148 (7) | 0.0323 (7) | 0.0010 (5) | −0.0057 (5) | −0.0003 (5) |
O4B | 0.0230 (6) | 0.0186 (7) | 0.0476 (9) | −0.0014 (5) | −0.0157 (6) | 0.0001 (6) |
C1B | 0.0182 (7) | 0.0179 (9) | 0.0261 (8) | 0.0013 (6) | −0.0019 (6) | 0.0017 (6) |
C2B | 0.0158 (7) | 0.0180 (9) | 0.0250 (8) | 0.0008 (6) | −0.0021 (5) | −0.0006 (6) |
C3B | 0.0171 (7) | 0.0163 (9) | 0.0289 (9) | −0.0003 (6) | −0.0019 (6) | 0.0020 (6) |
C4B | 0.0195 (7) | 0.0182 (9) | 0.0247 (8) | 0.0015 (6) | −0.0012 (6) | 0.0018 (6) |
N1A | 0.0221 (7) | 0.0196 (9) | 0.0387 (9) | −0.0001 (6) | −0.0073 (6) | 0.0024 (7) |
N2A | 0.0186 (7) | 0.0175 (8) | 0.0306 (8) | 0.0012 (5) | −0.0047 (5) | 0.0002 (6) |
N3A | 0.0215 (7) | 0.0175 (8) | 0.0319 (8) | 0.0009 (6) | −0.0037 (5) | 0.0007 (6) |
C1A | 0.0188 (7) | 0.0194 (9) | 0.0245 (8) | 0.0032 (6) | −0.0018 (5) | −0.0012 (6) |
C2A | 0.0176 (7) | 0.0218 (9) | 0.0300 (9) | 0.0007 (6) | −0.0033 (6) | −0.0021 (7) |
C3A | 0.0227 (8) | 0.0206 (10) | 0.0313 (9) | −0.0025 (6) | −0.0011 (6) | −0.0025 (7) |
O1B—H1B | 0.8200 | N1A—H1AA | 0.8600 |
O1B—C1B | 1.320 (2) | N1A—H1AB | 0.8600 |
O2B—C1B | 1.216 (2) | N1A—C1A | 1.339 (2) |
O3B—C4B | 1.272 (2) | N2A—H2A | 0.95 (3) |
O4B—C4B | 1.252 (2) | N2A—N3A | 1.362 (2) |
C1B—C2B | 1.507 (2) | N2A—C1A | 1.346 (2) |
C2B—H2BA | 0.9700 | N3A—H3A | 0.94 (3) |
C2B—H2BB | 0.9700 | N3A—C3A | 1.340 (2) |
C2B—C3B | 1.520 (2) | C1A—C2A | 1.399 (2) |
C3B—H3BA | 0.9700 | C2A—H2AA | 0.9300 |
C3B—H3BB | 0.9700 | C2A—C3A | 1.367 (3) |
C3B—C4B | 1.510 (2) | C3A—H3AA | 0.9300 |
C1B—O1B—H1B | 109.5 | H1AA—N1A—H1AB | 120.0 |
O1B—C1B—C2B | 117.32 (14) | C1A—N1A—H1AA | 120.0 |
O2B—C1B—O1B | 119.68 (15) | C1A—N1A—H1AB | 120.0 |
O2B—C1B—C2B | 123.00 (17) | N3A—N2A—H2A | 121.7 (17) |
C1B—C2B—H2BA | 109.0 | C1A—N2A—H2A | 126.8 (17) |
C1B—C2B—H2BB | 109.0 | C1A—N2A—N3A | 108.58 (14) |
C1B—C2B—C3B | 113.14 (14) | N2A—N3A—H3A | 122.1 (17) |
H2BA—C2B—H2BB | 107.8 | C3A—N3A—N2A | 108.22 (15) |
C3B—C2B—H2BA | 109.0 | C3A—N3A—H3A | 127.1 (17) |
C3B—C2B—H2BB | 109.0 | N1A—C1A—N2A | 122.17 (15) |
C2B—C3B—H3BA | 108.7 | N1A—C1A—C2A | 130.06 (15) |
C2B—C3B—H3BB | 108.7 | N2A—C1A—C2A | 107.76 (16) |
H3BA—C3B—H3BB | 107.6 | C1A—C2A—H2AA | 127.0 |
C4B—C3B—C2B | 114.39 (14) | C3A—C2A—C1A | 106.08 (15) |
C4B—C3B—H3BA | 108.7 | C3A—C2A—H2AA | 127.0 |
C4B—C3B—H3BB | 108.7 | N3A—C3A—C2A | 109.32 (17) |
O3B—C4B—C3B | 118.07 (14) | N3A—C3A—H3AA | 125.3 |
O4B—C4B—O3B | 122.26 (15) | C2A—C3A—H3AA | 125.3 |
O4B—C4B—C3B | 119.66 (16) | ||
O1B—C1B—C2B—C3B | −174.71 (17) | N2A—N3A—C3A—C2A | −1.2 (2) |
O2B—C1B—C2B—C3B | 5.4 (3) | N2A—C1A—C2A—C3A | 1.1 (2) |
C1B—C2B—C3B—C4B | −176.32 (15) | N3A—N2A—C1A—N1A | 178.99 (17) |
C2B—C3B—C4B—O3B | 170.20 (17) | N3A—N2A—C1A—C2A | −1.9 (2) |
C2B—C3B—C4B—O4B | −10.8 (3) | C1A—N2A—N3A—C3A | 1.9 (2) |
N1A—C1A—C2A—C3A | −179.8 (2) | C1A—C2A—C3A—N3A | 0.0 (2) |
Cg1 is the centroid of the pyrazolium ring. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1B—H1B···O3Bi | 0.82 | 1.79 | 2.5832 (18) | 164 |
N1A—H1AA···O4Bii | 0.86 | 2.08 | 2.874 (2) | 153 |
N1A—H1AB···O2Biii | 0.86 | 2.07 | 2.923 (2) | 170 |
N2A—H2A···O3Bii | 0.95 (3) | 1.76 (3) | 2.7132 (19) | 174 (3) |
N3A—H3A···O4Biv | 0.94 (3) | 1.79 (3) | 2.672 (2) | 156 (3) |
C2A—H2AA···O1Biii | 0.93 | 2.54 | 3.372 (2) | 148 |
C3A—H3AA···O2B | 0.93 | 2.47 | 3.214 (2) | 138 |
C3B—H3BA···Cg1v | 0.97 | 2.69 | 3.511 (2) | 142 |
Symmetry codes: (i) x, y−1, z; (ii) x+1/2, −y+3/2, z+1/2; (iii) x, y+1, z; (iv) x+1/2, −y+1/2, z+1/2; (v) x+3/2, y+3/2, z+1. |
Cg1 is the centroid of the pyrazolium ring. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1B—H1B···O3Bi | 0.82 | 1.79 | 2.5832 (18) | 164 |
N1A—H1AA···O4Bii | 0.86 | 2.08 | 2.874 (2) | 153 |
N1A—H1AB···O2Biii | 0.86 | 2.07 | 2.923 (2) | 170 |
N2A—H2A···O3Bii | 0.95 (3) | 1.76 (3) | 2.7132 (19) | 174 (3) |
N3A—H3A···O4Biv | 0.94 (3) | 1.79 (3) | 2.672 (2) | 156 (3) |
C2A—H2AA···O1Biii | 0.93 | 2.54 | 3.372 (2) | 148 |
C3A—H3AA···O2B | 0.93 | 2.47 | 3.214 (2) | 138 |
C3B—H3BA···Cg1v | 0.97 | 2.69 | 3.511 (2) | 142 |
Symmetry codes: (i) x, y−1, z; (ii) x+1/2, −y+3/2, z+1/2; (iii) x, y+1, z; (iv) x+1/2, −y+1/2, z+1/2; (v) x+3/2, y+3/2, z+1. |
Acknowledgements
TSY thanks the University of Mysore for research facilities and is also grateful to the Principal, Maharani's Science College for Women, Mysore, for giving permission to undertake research. JPJ acknowledges the NSF–MRI program (grant No. CHE-1039027) for funds to purchase the X-ray diffractometer.
References
Agilent (2012). CrysAlis PRO and CrysAlis RED. Agilent Technologies, Yarnton, England. Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Hall, A., Billinton, A., Brown, S. H., Clayton, N. M., Chowdhury, A., Giblin, G. M. P., Goldsmith, P., Isloor, A. M., Kalluraya, B. & Shetty, P. (2009). Eur. J. Med. Chem. 44, 3784–3787. Web of Science PubMed Google Scholar
Kavitha, C. N., Yathirajan, H. S., Narayana, B., Gerber, T., van Brecht, B. & Betz, R. (2013). Acta Cryst. E69, o260–o261. CSD CrossRef CAS IUCr Journals Google Scholar
Kettmann, V., Lokaj, J., Milata, V., Černuchová, P., Loupy, A. & Vo-Thanh, G. (2005). Acta Cryst. E61, o3852–o3854. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Koziol, A. E., Lis, T., Kolodziejczyk, E., Kusakiewicz-Dawid, A. & Rzeszotarska, B. (2006). Acta Cryst. E62, o3664–o3666. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Palatinus, L. & Chapuis, G. (2007). J. Appl. Cryst. 40, 786–790. Web of Science CrossRef CAS IUCr Journals Google Scholar
Parvez, M., Dalrymple, S. & Cote, A. (2001). Acta Cryst. E57, o163–o165. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Sauer, M., Porro, D., Mattanovich, D. & Branduaradi, P. (2008). Trends Biotechnol. 26, 100–108. Web of Science CrossRef PubMed CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Vinogradov, V. M., Dalinger, I. L. & Shevelev, S. A. (1994). Khim.-Farm. Zh. 28, 37–46. CAS Google Scholar
Yamuna, T. S., Jasinski, J. P., Scadova, D. R., Yathirajan, H. S. & Kaur, M. (2013). Acta Cryst. E69, o1425–o1426. CSD CrossRef CAS IUCr Journals Google Scholar
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